Examkin

Network Fundamentals

398 soru

Tüm türler398Çoktan seçmeli205Çoklu seçim92Sayısal18Eşleştirme68Sıralama7Kısa cevap8
Soru 141Soru →

A Cisco router interface GigabitEthernet0/1 has a burned-in MAC address of `0050.56a1.b2c3`. The interface is enabled and configured with the Cisco IOS command `ipv6 address fe80::/64 eui-64`. What is the complete compressed IPv6 link-local address assigned to this interface?

Cevabı ve açıklamayı göster

Cevap: fe80::250:56ff:fea1:b2c3; fe80::0250:56ff:fea1:b2c3; FE80::250:56FF:FEA1:B2C3; FE80::0250:56FF:FEA1:B2C3

Cevap

fe80::250:56ff:fea1:b2c3
The standard EUI-64 process converts the 48-bit MAC address `0050.56a1.b2c3` by inserting `FFFE` into the midpoint (`0050.56FF.FEa1.b2c3`) and inverting the 7th bit of the first byte (`00` hex = `00000000` binary -> `00000010` binary = `02` hex). Appending this 64-bit interface identifier `0250:56ff:fea1:b2c3` to the link-local prefix `fe80::/64` yields `fe80::250:56ff:fea1:b2c3` after omitting leading zeros.

Adım Adım Çözüm

1
Split the 48-bit MAC address into two 24-bit halves and insert the 16-bit hex value `FFFE` in the middle.
The MAC `0050.56a1.b2c3` becomes `0050:56FF:FEA1:B2C3`.
EUI-64 standard requires expanding a 48-bit MAC address into a 64-bit interface identifier by inserting `FFFE` between the OUI and the vendor-assigned NIC bytes.
2
Invert the 7th bit (Universal/Local bit) of the first byte.
First byte `00` (0000 000020000\ 0000_2) with the 7th bit inverted becomes `02` (0000 001020000\ 0010_2). The 64-bit Interface Identifier is `0250:56ff:fea1:b2c3`.
The 7th bit of the first byte indicates universal (00) vs local (11) scope; inverting 00 yields 11 (0202 hex).
3
Combine the link-local prefix `fe80::/64` with the generated EUI-64 interface identifier and apply standard IPv6 leading-zero compression.
`fe80::250:56ff:fea1:b2c3`
Link-local addresses always begin with `fe80::/64`, followed by the 64-bit interface identifier, suppressing leading zeros in hex quartets.

Anahtar Kavram

EUI-64 Link-Local IPv6 Address Calculation
Tahmini Süre:1m 30s
Soru 142Soru →

A Cisco Catalyst switch receives an Ethernet frame on interface GigabitEthernet0/12 configured as an access port in VLAN 30. The incoming frame has a source MAC address of 00e0.8b11.2233 and a destination MAC address of 00e0.8b99.8877. The switch's MAC address table currently contains no entries for interface GigabitEthernet0/12 and does not contain the destination MAC address. Which two actions does the switch perform upon receiving this frame? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The switch records the source MAC address 00e0.8b11.2233 associated with interface GigabitEthernet0/12 in its VLAN 30 MAC address table.; The switch floods the frame out all operational ports assigned to VLAN 30, excluding the receiving interface GigabitEthernet0/12.

Cevap

The switch records the source MAC address 00e0.8b11.2233 associated with interface GigabitEthernet0/12 in its VLAN 30 MAC address table, and floods the frame out all operational ports assigned to VLAN 30, excluding the receiving interface GigabitEthernet0/12.
When a switch receives a frame, it performs two distinct steps: MAC learning based on the source MAC address, and frame forwarding based on the destination MAC address. First, it records the source MAC address 00e0.8b11.2233 and its associated ingress port GigabitEthernet0/12 in the MAC table for VLAN 30. Second, because the destination MAC address 00e0.8b99.8877 is not in the MAC table, the switch handles it as unknown unicast traffic by flooding it to all other active ports configured in VLAN 30, excluding ingress port GigabitEthernet0/12.

Adım Adım Çözüm

1
Examine source MAC address processing.
The switch reads source MAC 00e0.8b11.2233 on ingress interface GigabitEthernet0/12 (VLAN 30) and updates its MAC address table entry for VLAN 30.
MAC address table learning is performed based on the source MAC address of incoming frames.
2
Examine destination MAC address lookup.
Because destination MAC 00e0.8b99.8877 is not in the MAC address table for VLAN 30, the frame is classified as unknown unicast.
Unknown unicast frames must be flooded within the VLAN scope.
3
Determine forwarding interface scope.
The frame is forwarded to all active ports in VLAN 30 except ingress port GigabitEthernet0/12.
Flooding rules dictate forwarding to all ports in the same broadcast domain except the receiving port.

Anahtar Kavram

L2 Switching MAC Address Table Learning and Unknown Unicast Flooding
Soru 143Soru →

A network administrator needs to segment a local network into distinct broadcast domains to prevent excessive broadcast traffic from degrading performance. Which network device natively creates a separate broadcast domain on each of its physical interfaces?

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Cevap: Router

Cevap

The router is the network component that natively creates separate broadcast domains on each of its physical interfaces.
Routers operate at Layer 3 of the OSI model and separate networks into distinct IP subnets. Because routers do not forward Layer 2 broadcast packets by default, each physical interface on a router forms a separate broadcast domain.

Adım Adım Çözüm

1
Identify the OSI layer boundary required to block Layer 2 broadcast traffic.
Layer 3 (Network Layer) boundaries prevent Layer 2 broadcast frames (such as MAC address FF:FF:FF:FF:FF:FF) from passing between connected networks.
Broadcast traffic is confined to its local subnet unless specifically routed or relayed by design.
2
Determine which component performs default Layer 3 boundary isolation.
Routers connect independent Layer 3 networks and terminate Layer 2 broadcast domains on each interface.
Each physical interface of a router is assigned to a distinct IP subnet and acts as an independent broadcast domain boundary.

Anahtar Kavram

Broadcast Domain Isolation at Layer 3
Tahmini Süre:45s
Soru 144Soru →

Under the Cisco Split-MAC architecture, a Lightweight Access Point (LAP) operates in Local mode. Which task is handled directly by the access point rather than being offloaded to the Wireless LAN Controller (WLC)?

Cevabı ve açıklamayı göster

Cevap: Transmitting 802.11 beacon frames and responding to probe requests

Cevap

Transmitting 802.11 beacon frames and responding to probe requests is performed locally by the Lightweight Access Point.
Transmitting 802.11 beacon frames and responding to probe requests are time-sensitive real-time MAC functions handled locally by the access point hardware in Split-MAC architecture.

Adım Adım Çözüm

1
Identify the role of Split-MAC architecture
Split-MAC divides 802.11 protocol functions between real-time MAC functions on the AP and management MAC functions on the WLC.
Real-time duties requiring immediate time-sensitive transmission are assigned directly to the AP hardware.
2
Differentiate AP duties from WLC duties
Beacons, probe responses, and frame acknowledgment occur on the AP, whereas authentication, association, and frame bridging occur on the WLC.
This allows central management of security and policy while offloading high-frequency time-critical RF duties to the AP.

Anahtar Kavram

Split-MAC Architecture and Real-Time vs Management MAC Duties
Soru 145Soru →

An enterprise network deployment hosts multiple business-critical server workloads on a bare-metal Type 1 hypervisor. The hypervisor is connected via a dual-homed physical 10GbE uplink to an upstream Layer 3 switch. Inside the hypervisor, a internal virtual switch (vSwitch) connects multiple virtual machines (VMs) assigned to VLAN 10. If a virtual machine on VLAN 10 emits an Ethernet broadcast frame (destination MAC FF:FF:FF:FF:FF:FF) during an ARP resolution request, how do these virtual and physical infrastructure components process and scope the broadcast traffic?

Cevabı ve açıklamayı göster

Cevap: The virtual switch forwards the broadcast frame to all other VM virtual interfaces assigned to VLAN 10 on that host and out the physical uplink to the Layer 3 switch, where the switch processes the frame at Layer 2 across VLAN 10 ports but does not forward it across routed Layer 3 boundaries.

Cevap

The virtual switch forwards the broadcast frame to all other virtual machine interfaces in VLAN 10 and out the physical uplink to the Layer 3 switch, which confines the broadcast within VLAN 10 and does not forward it across Layer 3 routed boundaries.
A Layer 2 virtual switch integrated into a Type 1 bare-metal hypervisor operates as a standard bridge. When a VM issues a broadcast frame, the vSwitch floods it to all vNICs in the same VLAN and out the physical network interface card (pNIC) uplink. Upon reaching the physical Layer 3 switch, the frame is flooded only across ports belonging to VLAN 10. The Layer 3 boundaries on the switch terminate the broadcast, preventing it from reaching other VLANs or subnets.

Adım Adım Çözüm

1
Analyze the role and operation of the internal virtual switch (vSwitch) in a Type 1 hypervisor.
The vSwitch acts as a software-based Layer 2 switch operating directly on bare-metal hardware. It maintains a MAC address table per VLAN and floods Layer 2 broadcast frames (FF:FF:FF:FF:FF:FF) to all local vNIC ports in the same VLAN and out physical uplinks.
Virtual switches follow standard IEEE Layer 2 bridging behaviors within configured VLAN boundaries.
2
Evaluate the forwarding behavior of the physical Layer 3 switch upon receiving the broadcast frame over the physical uplink.
The Layer 3 switch floods the broadcast frame to all physical ports participating in VLAN 10 within that Layer 2 broadcast domain, but terminates the broadcast at its Layer 3 switch virtual interface (SVI) or routed interfaces.
Layer 3 boundaries (routers/SVIs) isolate broadcast domains and prevent Layer 2 broadcasts from traversing into other subnets.

Anahtar Kavram

Layer 2 Broadcast Domain Scoping in Virtual and Physical Network Components
Soru 146Soru →

Refer to the following Cisco IOS CLI output from switch Switch-A:

text
Switch-A# show interfaces fastEthernet 0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0007.ebaa.1101
Full-duplex, 100Mb/s, media type is 100BASE-TX
...
12540 input errors, 12538 CRC, 0 frame, 0 overrun, 0 ignored
0 output errors, 0 collisions, 0 late collisions, 0 deferred

Switch-A connects directly to Switch-B over a 10-meter Category 5e UTP cable. Switch-B reports high counts of late collisions on its corresponding interface. Which condition is the root cause of these interface symptoms?

Cevabı ve açıklamayı göster

Cevap: A duplex mismatch where Switch-A is operating in full-duplex mode and Switch-B is operating in half-duplex mode.

Cevap

The root cause is a duplex mismatch where Switch-A is set to full-duplex and Switch-B is set to half-duplex.
A duplex mismatch occurs when one end of an Ethernet link operates in full-duplex mode while the opposite end operates in half-duplex mode. Because the full-duplex device (Switch-A) transmits data without performing carrier sensing, it frequently sends frames while the half-duplex device (Switch-B) is actively transmitting. This causes Switch-B to detect collisions after sending the initial 64 bytes of a frame (late collisions), while Switch-A receives aborted frame fragments from Switch-B, registering them as CRC and FCS input errors.

Adım Adım Çözüm

1
Analyze the CLI output on Switch-A
The interface is operating in full-duplex mode with a high number of input errors dominated by CRC errors, while output errors and collisions remain at zero.
An interface configured for full-duplex never checks for carrier sensing or collisions, so its collision counters will always remain zero.
2
Analyze the reported symptoms on Switch-B
Switch-B reports high counts of late collisions.
Late collisions occur on half-duplex interfaces when another device transmits after the 64-byte slot time window has passed.
3
Correlate symptoms across both devices
Full-duplex on Switch-A + Half-duplex on Switch-B explains both CRC errors on Switch-A and late collisions on Switch-B.
Switch-A transmits whenever it has data without listening. When Switch-B is transmitting, Switch-A's concurrent transmission collides with Switch-B's frames, causing Switch-B to record late collisions and Switch-A to receive truncated/corrupted frame fragments resulting in CRC errors.

Anahtar Kavram

Duplex Mismatch Symptom Analysis
Tahmini Süre:2m 0s
Soru 147Soru →

An organization is designing its enterprise edge network architecture. The design places a Layer 3 switch in the distribution layer to route traffic between local VLANs and places a Next-Generation Firewall (NGFW) at the WAN/Internet perimeter. Which statement correctly distinguishes the operational role of the Next-Generation Firewall from that of the Layer 3 switch in this deployment?

Cevabı ve açıklamayı göster

Cevap: The Next-Generation Firewall performs deep packet inspection up to Layer 7 for application awareness and threat prevention, whereas the Layer 3 switch primarily performs high-speed packet forwarding based on Layer 3 IP routing headers.

Cevap

The Next-Generation Firewall performs deep packet inspection up to Layer 7 for application awareness and threat prevention, whereas the Layer 3 switch primarily performs high-speed packet forwarding based on Layer 3 IP routing headers.
Next-Generation Firewalls operate at perimeter boundaries to provide stateful inspection and Layer 7 application awareness, ensuring robust security enforcement. In contrast, Layer 3 switches are optimized for high-speed inter-VLAN routing and packet forwarding using Layer 3 IP header information.

Adım Adım Çözüm

1
Identify the primary operational role of a Layer 3 switch.
Layer 3 switches combine Layer 2 switching capabilities with hardware-accelerated Layer 3 routing (IP packet forwarding across subnets/VLANs).
Layer 3 switches focus on wire-speed intra-campus and inter-VLAN routing.
2
Identify the primary operational role of a Next-Generation Firewall (NGFW).
NGFWs provide stateful packet inspection, application-layer control (Layer 7), intrusion prevention systems (IPS), and threat protection at security boundaries.
NGFWs focus on security enforcement and deep packet analysis at edge or boundary locations.
3
Compare the distinct roles to select the correct functional distinction.
The firewall inspects up to Layer 7 for security threats, while the Layer 3 switch routes traffic based on Layer 3 IP headers.
This captures the fundamental functional separation between core routing hardware and perimeter security components.

Anahtar Kavram

Distinct Roles of Network Components (Layer 3 Switches vs. Next-Generation Firewalls)
Soru 148Soru →

An administrator observes intermittent data corruption and dropped frames on interface `GigabitEthernet0/1` of an enterprise switch. Executing the `show interfaces GigabitEthernet0/1` command yields the following output:

text
GigabitEthernet0/1 is up, line protocol is up (connected)
Hardware is GigabitEthernet, address is 0012.7f3e.a101
Full-duplex, 1000Mb/s, media type is 1000BaseTX
Input queue: 0/75/0/0; Total output drops: 0
5 minute input rate 12000 bits/sec, 15 packets/sec
5 minute output rate 11000 bits/sec, 14 packets/sec
124501 packets input, 15890123 bytes
0 runts, 0 giants, 0 throttles
4812 input errors, 4812 CRC, 0 frame, 0 overrun, 0 ignored
0 output errors, 0 collisions, 0 late collision

Based on the CLI output, what is the most likely root cause of the reported interface errors?

Cevabı ve açıklamayı göster

Cevap: Physical cable damage or electromagnetic interference causing signal corruption along the Ethernet run

Cevap

Physical cable damage or electromagnetic interference causing signal corruption along the Ethernet run
The correct answer identifies physical cable damage or electromagnetic interference as the root cause. In Cisco IOS, Cyclic Redundancy Check (CRC) errors increment when a received frame fails its checksum verification. When CRC errors increase while collision and late collision counters remain at zero, the cause is physical layer corruption—such as defective copper wiring, faulty RJ-45 crimping, damaged cable shielding, or external electrical noise.

Adım Adım Çözüm

1
Analyze the interface status and error counters in the CLI snippet.
The interface is operating in full-duplex at 1000 Mbps with `line protocol is up`. Input errors precisely match 4,812 Cyclic Redundancy Check (CRC) errors, while collision and late collision counters remain at 0.
CRC errors occur when the frame check sequence (FCS) calculated by the receiving interface does not match the FCS field attached by the sender.
2
Evaluate potential Layer 1 vs. Layer 2 failure modes.
Because late collisions are 0 and collisions are 0, duplex mismatch and excessive cable length issues are ruled out.
Duplex mismatches cause late collisions on full-duplex interfaces and collisions/runts on half-duplex interfaces.
3
Determine the physical cause of checksum failures.
Isolated CRC errors on an Ethernet interface are directly tied to physical media defects, bad shielding, loose RJ-45 connectors, or electrical noise (EMI).
Corrupted bits during transmission alter the mathematical CRC value without triggering collision detection circuits.

Anahtar Kavram

CRC errors in Cisco IOS indicate corrupt frames received over the physical link, most commonly caused by damaged cabling, improper shielding, EMI, or loose pin connections.
Soru 149Soru →

A host network interface is configured with the MAC address 0011.2233.4455. When the host generates a 64-bit IPv6 interface identifier using the standard EUI-64 process, which value is created?

Cevabı ve açıklamayı göster

Cevap: 0211:22FF:FE33:4455

Cevap

The interface identifier created using EUI-64 is 0211:22FF:FE33:4455.
The correct answer properly demonstrates both required steps of the EUI-64 derivation: inserting the 16-bit hexadecimal sequence FFFE into the middle of the 48-bit MAC address and inverting the 7th bit (Universal/Local bit) of the first byte from 0 to 1 (changing 0x00 to 0x02).

Adım Adım Çözüm

1
Split the 48-bit MAC address into two 24-bit halves.
Left half: 00-11-22, Right half: 33-44-55
EUI-64 requires inserting a 16-bit hexadecimal marker in the middle of the MAC address.
2
Insert hexadecimal FFFE into the middle between the two halves.
00-11-22-FF-FE-33-44-55
The EUI-64 standard specifies FFFE as the constant padding value to expand a 48-bit MAC address to 64 bits.
3
Invert the 7th bit (Universal/Local bit) of the first byte.
First byte 00 (00000000 in binary) becomes 02 (00000010 in binary). Combining and formatting into IPv6 hex quads produces 0211:22FF:FE33:4455.
Inverting the 7th bit changes the scope from globally unique (0) to locally managed (1) for EUI-64 derived addresses.

Anahtar Kavram

EUI-64 Interface ID Generation
Soru 150Soru →

A network engineer is configuring an interface on a Cisco router servicing an internal LAN segment. The interface is assigned the IPv4 address 192.168.1.37192.168.1.37 with a subnet mask of 255.255.255.240255.255.255.240 (/28/28). Which IPv4 address represents the broadcast address for this subnetwork?

Cevabı ve açıklamayı göster

Cevap: 192.168.1.47192.168.1.47

Cevap

192.168.1.47192.168.1.47
The subnet mask 255.255.255.240255.255.255.240 (/28/28) provides a block size of 16 addresses per subnet. Multiples of 16 in the 4th octet yield network addresses of 192.168.1.0192.168.1.0, 192.168.1.16192.168.1.16, 192.168.1.32192.168.1.32, and 192.168.1.48192.168.1.48. The host 192.168.1.37192.168.1.37 resides in the 192.168.1.32/28192.168.1.32/28 subnet, making 192.168.1.47192.168.1.47 the broadcast address.

Adım Adım Çözüm

1
Determine the block size from the subnet mask.
A subnet mask of 255.255.255.240255.255.255.240 corresponds to a /28/28 prefix, leaving 32−28=432 - 28 = 4 host bits. The block size is 24=162^4 = 16.
Calculating the block size defines the increment between subnetwork boundaries.
2
Identify the network boundary for IP address 192.168.1.37192.168.1.37.
Subnet multiples of 16 in the 4th octet are 0, 16, 32, 48. Since 37 falls between 32 and 47, the subnetwork ID is 192.168.1.32192.168.1.32.
The network address is the lowest boundary address for the subnet.
3
Calculate the broadcast address for the subnet.
The broadcast address is one less than the next network address (192.168.1.48−1=192.168.1.47192.168.1.48 - 1 = 192.168.1.47).
The broadcast address is the highest address in the block with all host bits set to 1.

Anahtar Kavram

IPv4 Subnet Masking and Broadcast Address Calculation
Tahmini Süre:1m 0s
Soru 151Soru →

During an operational review of network infrastructure policies across an enterprise gateway router, a network specialist is defining classification parameters for transport layer protocols. Which two statements accurately describe the architectural characteristics and operational mechanics of the User Datagram Protocol (UDP) compared to Transmission Control Protocol (TCP)? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: UDP operates as a connectionless protocol that avoids state maintenance and establishment handshakes prior to transmitting data.; UDP utilizes a fixed 8-byte header field structure that lacks sequence numbering and receiver window fields.

Cevap

The correct statements are that UDP operates as a connectionless protocol without maintaining connection state, and that UDP utilizes a compact fixed 8-byte header that excludes sequence numbers and windowing controls.
The statements confirming UDP's connectionless operation and its fixed 8-byte header without sequence or window fields are correct. UDP avoids pre-transmission handshakes to reduce latency and maintains minimal protocol overhead by using an 8-byte header consisting solely of Source Port, Destination Port, Length, and Checksum.

Adım Adım Çözüm

1
Analyze transport layer connection initialization characteristics for UDP.
UDP is connectionless, requiring no initial three-way handshake (SYN, SYN-ACK, ACK) or state table allocation on network interfaces.
Connecting endpoints can immediately send datagrams without setup delay.
2
Examine the transport header structure of UDP versus TCP.
A standard UDP header consists of 4 fields (Source Port, Destination Port, Length, Checksum) totaling 8 bytes, whereas TCP headers are at least 20 bytes long and include Sequence Number, Acknowledgment Number, Window Size, and Control Flags.
Lacking sequence numbers and windowing fields keeps the UDP header minimal.
3
Evaluate transport-layer reliability and flow control features in UDP.
UDP offers best-effort delivery without built-in segment retransmission, sequencing, or windowing flow control mechanisms.
Protocol mechanisms like retransmission and dynamic sliding windows belong to TCP.

Anahtar Kavram

UDP vs TCP Transport Protocol Characteristics and Header Comparison
Soru 152Soru →

A network administrator is assigning a private IPv4 host address within the 172.16.0.0/12172.16.0.0/12 range for a branch office subnet defined as 172.30.50.16/28172.30.50.16/28. Which IPv4 address is a valid usable host address for a device in this subnet?

Cevabı ve açıklamayı göster

Cevap: 172.30.50.25172.30.50.25

Cevap

The address 172.30.50.25172.30.50.25 is a valid usable host IPv4 address within the 172.30.50.16/28172.30.50.16/28 subnet.
The subnet 172.30.50.16/28172.30.50.16/28 has a block size of 1616 addresses (242^4), covering 172.30.50.16172.30.50.16 through 172.30.50.31172.30.50.31. Subtracting the network address (172.30.50.16172.30.50.16) and broadcast address (172.30.50.31172.30.50.31) leaves a usable host range of 172.30.50.17172.30.50.17 to 172.30.50.30172.30.50.30. The address 172.30.50.25172.30.50.25 lies within this valid host range and is within the RFC 1918 private block (172.16.0.0/12172.16.0.0/12).

Adım Adım Çözüm

1
Determine the network properties for 172.30.50.16/28172.30.50.16/28.
A /28/28 subnet mask has 32−28=432 - 28 = 4 host bits, yielding a block size of 24=162^4 = 16.
The block size dictates the increment between subnets.
2
Identify the network address, broadcast address, and usable host range.
Network Address: 172.30.50.16172.30.50.16; Broadcast Address: 172.30.50.31172.30.50.31; Usable Host Range: 172.30.50.17172.30.50.17 to 172.30.50.30172.30.50.30.
The network address is the first address in the block, and the broadcast address is the last address in the block.
3
Verify RFC 1918 private address range compliance and match against options.
The range 172.16.0.0/12172.16.0.0/12 spans 172.16.0.0172.16.0.0 to 172.31.255.255172.31.255.255. The address 172.30.50.25172.30.50.25 is both within the RFC 1918 block and within the usable host range 172.30.50.17172.30.50.17 - 172.30.50.30172.30.50.30.
Only valid usable host addresses within the private range can be assigned to host interfaces.

Anahtar Kavram

IPv4 Subnet Boundaries and RFC 1918 Private Addressing
Soru 153Soru →

A network administrator executes the command `show interface GigabitEthernet0/0` on a Cisco router and notes a MAC address of `a1b2.c3d4.e5f6`. The interface is then configured with the command `ipv6 address 2001:db8:1111:2222::/64 eui-64`. Which IPv6 global unicast address will be generated on this interface?

Cevabı ve açıklamayı göster

Cevap: 2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6

Cevap

2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6
Generating an IPv6 EUI-64 interface identifier requires splitting the 48-bit MAC address (a1:b2:c3:d4:e5:f6) into two 24-bit halves, inserting FFFE in the middle (a1b2:c3ff:fed4:e5f6), and flipping the 7th bit (Universal/Local bit) of the first byte. Converting 0xa1 (10100001 in binary) to invert the 7th bit yields 0xa3 (10100011 in binary). Combining the prefix 2001:db8:1111:2222::/64 with the modified interface ID gives 2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6.

Adım Adım Çözüm

1
Split MAC address into OUI and NIC identifier halves
OUI portion is a1:b2:c3 and NIC portion is d4:e5:f6
EUI-64 insertion occurs directly between the 24-bit OUI and the 24-bit device identifier.
2
Insert the 16-bit hex value FFFE between the two halves
a1b2:c3ff:fed4:e5f6
EUI-64 expands a 48-bit MAC address into a 64-bit interface identifier by adding 0xFFFE.
3
Invert the 7th bit (Universal/Local bit) of the first byte (0xa1)
0xa1 in binary is 10100001. Inverting the 7th bit yields 10100011, which is 0xa3.
IEEE EUI-64 standard requires flipping the Universal/Local (U/L) bit so that 0 (universal) becomes 1 (locally administered scope for auto-configured interfaces).
4
Combine configured /64 prefix with generated 64-bit interface ID
2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6
The prefix 2001:db8:1111:2222::/64 forms the first 64 bits and the modified EUI-64 ID forms the last 64 bits.

Anahtar Kavram

EUI-64 Interface Identifier Generation
Tahmini Süre:1m 30s
Soru 154Soru →

A network administrator is designing an IPv4 addressing plan for a new office department. The department requires static host IP assignments for 61 client workstations, 1 default gateway router interface, and 1 network printer, requiring a total of 63 active host IP addresses. Which subnet mask provides the most efficient address space utilization while satisfying all required host addresses?

Cevabı ve açıklamayı göster

Cevap: 255.255.255.128255.255.255.128

Cevap

The subnet mask 255.255.255.128255.255.255.128 (corresponding to a /25/25 prefix) is the most efficient subnet mask that accommodates 63 host IP addresses.
To support 63 active host interfaces, the subnet must provide at least 63 usable IPv4 addresses. Using 6 host bits yields 26−2=622^6 - 2 = 62 usable addresses, which falls 1 short. Therefore, 7 host bits are required (27−2=1262^7 - 2 = 126 usable addresses). A subnet with 7 host bits leaves 25 prefix bits (32−7=2532 - 7 = 25), corresponding to the dotted-decimal subnet mask 255.255.255.128255.255.255.128. This is the smallest subnet that satisfies the requirement without wasting excessive IP addresses.

Adım Adım Çözüm

1
Determine total required host IP addresses
61 workstations+1 gateway+1 printer=63 usable host IP addresses61 \text{ workstations} + 1 \text{ gateway} + 1 \text{ printer} = 63 \text{ usable host IP addresses}
Every device and gateway interface requiring an IP address counts toward the total host capacity.
2
Calculate required host bits using the usable host capacity formula 2H−2≥632^H - 2 \ge 63
For H=6H = 6: 26−2=622^6 - 2 = 62 usable addresses (insufficient). For H=7H = 7: 27−2=1262^7 - 2 = 126 usable addresses (sufficient).
Two IP addresses in every subnet are reserved for the network ID and broadcast address.
3
Derive prefix length and dotted-decimal subnet mask
Prefix length =32−7=/25= 32 - 7 = /25, which converts to 255.255.255.128255.255.255.128
Subtracting 7 host bits from 32 total IPv4 bits leaves 25 network bits.

Anahtar Kavram

Usable IPv4 Host Address Calculation (2H−22^H - 2) and Subnet Mask Derivation
Soru 155Soru →

An enterprise network team is deploying a virtualized data center infrastructure to support high-performance database workloads. The design requires a hypervisor deployment that operates directly on bare-metal server hardware without relying on an underlying host operating system to maximize resource efficiency and reduce overhead. Which hypervisor architecture meets these requirements, and what is its primary operational characteristics?

Cevabı ve açıklamayı göster

Cevap: A Type 1 hypervisor, which installs directly on the bare-metal hardware and manages guest operating systems directly.

Cevap

A Type 1 hypervisor, which installs directly on the bare-metal hardware and manages guest operating systems directly.
The correct option correctly identifies a Type 1 hypervisor, also known as a bare-metal hypervisor. It runs directly on host server hardware, giving guest virtual machines direct access to compute and hardware resources while minimizing performance overhead.

Adım Adım Çözüm

1
Analyze the operational requirements provided in the scenario.
The requirements demand a hypervisor that runs directly on server hardware (bare-metal) without an underlying host operating system to eliminate unnecessary latency and OS overhead.
Enterprise virtualized server environments hosting high-performance workloads require direct hardware abstraction and direct access to CPU, memory, and storage.
2
Distinguish between hypervisor types and network device roles.
Type 1 (bare-metal) hypervisors sit directly on host hardware. Type 2 (hosted) hypervisors require a host OS. Switches and discovery protocols handle network traffic forwarding and discovery, not host server virtualization.
Understanding component roles ensures selecting the architecture designed for bare-metal virtualization.

Anahtar Kavram

Hypervisor Architecture Types and Roles (Type 1 vs. Type 2)
Tahmini Süre:1m 30s
Soru 156Soru →

An enterprise network engineer is designing a branch office infrastructure with three specific requirements:
1. Virtualized server workloads must run directly on bare-metal hardware without an intermediate operating system layer.
2. Local VLAN broadcast domains must be segmented and routed at hardware wire speed using specialized Application-Specific Integrated Circuits (ASICs).
3. Wireless Access Points (APs) managed by a centralized Wireless LAN Controller (WLC) must continue switching local client traffic locally if the WAN connection to the central controller fails.

Which combination of network component operational roles and architecture satisfies all of these requirements?

Cevabı ve açıklamayı göster

Cevap: Deploy Type 1 hypervisors on server hardware, perform inter-VLAN routing using Layer 3 switches, and configure lightweight APs in FlexConnect mode.

Cevap

Deploy Type 1 hypervisors on server hardware, perform inter-VLAN routing using Layer 3 switches, and configure lightweight APs in FlexConnect mode.
The correct selection combines Type 1 bare-metal hypervisors (which run directly on physical hardware), Layer 3 switches (which use dedicated ASICs to perform high-speed inter-VLAN routing across broadcast domains), and FlexConnect AP mode (which enables local traffic switching at branch offices during WLC controller outages).

Adım Adım Çözüm

1
Identify the virtualization requirement.
Direct execution on bare-metal hardware without a host OS requires a Type 1 (bare-metal) hypervisor, such as VMware ESXi or Cisco UCS B-Series hypervisors.
Type 2 hypervisors require an underlying host OS (e.g., Windows/Linux), adding overhead.
2
Identify the routing component requirement.
Wire-speed inter-VLAN packet forwarding using hardware ASICs requires a Layer 3 switch (multilayer switch).
Layer 2 switches do not perform IP routing between subnets, while software-based routers lack hardware ASIC switching tables for high-density campus LANs.
3
Identify the wireless AP mode requirement.
FlexConnect mode (formerly REAP) allows lightweight APs to switch client data traffic locally when the CAPWAP control tunnel to the WLC is disrupted.
Local mode APs drop client traffic or cease forwarding when CAPWAP connection to the WLC drops.

Anahtar Kavram

Network Component Roles and Virtualization Architecture
Tahmini Süre:1m 30s
Soru 157Soru →

An enterprise network architect is auditing a virtualized campus network deployment. A database workload runs inside a virtual machine (VM) hosted on a bare-metal (Type 1) hypervisor. The hypervisor's virtual switch (vSwitch) is connected via an 802.1Q trunk link to a physical Layer 2 access switch, which in turn connects to a Layer 3 switch serving as the default gateway. If the VM sends a Layer 2 ARP broadcast frame to locate its default gateway, which statement correctly describes how network components handle this broadcast frame?

Cevabı ve açıklamayı göster

Cevap: The Type 1 hypervisor's vSwitch forwards the broadcast frame across the trunk to the Layer 2 switch, which floods it out all active ports in the same VLAN, while the Layer 3 switch interface processes the frame but does not forward the broadcast beyond the subnet.

Cevap

The Type 1 hypervisor's vSwitch forwards the broadcast frame across the trunk to the Layer 2 switch, which floods it out all active ports in the same VLAN, while the Layer 3 switch interface processes the frame but does not forward the broadcast beyond the subnet.
A Layer 2 broadcast frame (such as an ARP request) is flooded by both virtual switches (vSwitches inside a Type 1 hypervisor) and physical Layer 2 switches to all active ports within the assigned VLAN. The Layer 3 device processes the ARP request to reply with its MAC address, but boundaried Layer 3 interfaces strictly restrict broadcast frames from being forwarded outside their local subnet.

Adım Adım Çözüm

1
Analyze the role of the Type 1 hypervisor vSwitch
The Type 1 bare-metal hypervisor directly controls hardware resources. Its internal virtual switch operates as a standard Layer 2 switch, forwarding the VM's Layer 2 broadcast frame out the physical uplink trunk connected to the access switch.
Type 1 hypervisors do not require a host OS, and vSwitches maintain Layer 2 VLAN segregation and broadcast functionality.
2
Evaluate the forwarding behavior of the physical Layer 2 switch
The physical Layer 2 access switch receives the broadcast frame on the 802.1Q trunk and floods it to all other operational access and trunk ports belonging to that specific VLAN.
Switches separate collision domains per port but preserve broadcast domains per VLAN.
3
Determine the boundary behavior at the Layer 3 gateway switch
The Layer 3 switch receives the ARP request on its Switched Virtual Interface (SVI) or routed port for that VLAN, processes the ARP broadcast locally to send an ARP response, but does not forward the broadcast frame to any other IP interfaces/subnets.
Layer 3 boundaries (routed interfaces and SVIs) define the edge of a Layer 2 broadcast domain.

Anahtar Kavram

Collision vs Broadcast Domains across Physical and Virtual Components
Tahmini Süre:2m 0s
Soru 158Soru →

A network technician observes high counts of late collisions and Frame Check Sequence (FCS) errors on a switch interface connected to a server. A CLI check shows the interface output below:

text
FastEthernet0/1 is up, line protocol is up (connected)
Full-duplex, 100Mb/s, media type is 100BaseTX
542 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
1243 output errors, 891 late collisions

Which physical or data-link issue is the most likely cause of these interface error statistics?

Cevabı ve açıklamayı göster

Cevap: A duplex mismatch between the switch interface and the connected device

Cevap

A duplex mismatch between the switch interface and the connected device is the primary cause of late collisions and FCS errors.
A duplex mismatch occurs when one end of an Ethernet link operates in full-duplex while the opposite end operates in half-duplex. The full-duplex device transmits data whenever ready without checking for carrier activity. When the half-duplex device is transmitting and receives data from the full-duplex device after sending its initial 64 bytes, it records a late collision.

Adım Adım Çözüm

1
Analyze the interface error counters in the CLI output.
Identified high late collisions and output errors on an operational (up/up) link.
Late collisions occur when a collision is detected after the first 64 bytes (512 bits) of a frame have been transmitted.
2
Correlate late collision symptoms with duplex settings.
Determined that one end is operating in full-duplex while the remote end is operating in half-duplex.
The full-duplex end sends traffic without listening for carrier sense, causing the half-duplex end to transmit simultaneously and register late collisions.

Anahtar Kavram

Duplex Mismatch Symptoms and Interface Error Counters
Soru 159Soru →

An engineer is troubleshooting severe frame corruption and packet drops on a GigabitEthernet connection between a Catalyst switch and an enterprise router. Both interfaces are explicitly configured for 1000Mb/s Full-duplex. The CLI output from the switch is shown below:

text
GigabitEthernet0/1 is up, line protocol is up
Hardware is Gigabit Ethernet, address is 5006.ab12.cd34 (bia 5006.ab12.cd34)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
5 minute input rate 452000 bits/sec, 510 packets/sec
5 minute output rate 489000 bits/sec, 540 packets/sec
1245012 packets input, 1084201948 bytes, 0 no buffer
0 runts, 0 giants, 0 throttles
14205 input errors, 14205 CRC, 0 frame, 0 overrun, 0 ignored
1589022 packets output, 1482910244 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets

Physical inspection reveals that a custom UTP patch cable was wired using non-standard pin pairings where pins 3 and 6 were split across different wire pairs instead of sharing a single twisted pair. Which physical or data link issue is directly responsible for the high number of CRC errors observed on this full-duplex interface?

Cevabı ve açıklamayı göster

Cevap: Severe near-end crosstalk (NEXT) and electromagnetic interference caused by the split-pair Ethernet cable pinout mismatch.

Cevap

Severe near-end crosstalk (NEXT) and electromagnetic interference caused by the split-pair Ethernet cable pinout mismatch.
The correct answer identifies signal degradation and crosstalk resulting from split-pair cabling as the root cause of the CRC errors. Twisted-pair Ethernet (such as 1000BASE-T) relies on differential signaling across twisted pairs to neutralize electromagnetic interference. Splitting pins 3 and 6 across separate pairs destroys signal cancellation, producing high rates of Near-End Crosstalk (NEXT). When frames arrive corrupted, the receiving NIC's Frame Check Sequence (FCS) calculation fails, incrementing the CRC input error counter while collision counters remain zero due to full-duplex operation.

Adım Adım Çözüm

1
Analyze the interface statistics from the 'show interfaces' CLI snippet.
The interface is operating in Full-duplex at 1000Mb/s with line protocol up. There are 14,205 input errors, all of which are specifically CRC errors, while collision counts are 0.
Full-duplex interfaces disable collision detection mechanisms because transmission and reception occur over separate dedicated pairs. Therefore, collisions are not expected.
2
Evaluate the physical cabling scenario described in the stem.
The custom cable has split pairs across pins 3 and 6 (transmitting signals over wires from different twisted pairs).
Twisted pair cabling relies on balanced differential signaling to cancel out noise and crosstalk. When a pair is split, differential cancellation fails, creating massive Near-End Crosstalk (NEXT).
3
Correlate physical layer noise with interface error counters.
NEXT corrupts electrical signals during transit, causing the receiving interface to compute a Frame Check Sequence (FCS) that does not match the trailer, generating CRC errors.
CRC errors without collisions or late collisions on a full-duplex link are a classic sign of Layer 1 physical medium defects, such as cable damage or pinout/twist errors.

Anahtar Kavram

Twisted Pair Cable Pinout Mechanics & Interface Error Counter Diagnosis
Tahmini Süre:2m 0s
Soru 160Soru →

A network administrator is troubleshooting poor network performance on a switch interface connected to an end host. Executing the `show interfaces GigabitEthernet0/1` command produces the following output:

text
GigabitEthernet0/1 is up, line protocol is up
Hardware is Gigabit Ethernet, address is 0011.bb22.c334 (bia 0011.bb22.c334)
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:02, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
5 minute input rate 32000 bits/sec, 24 packets/sec
5 minute output rate 98000 bits/sec, 65 packets/sec
521405 packets input, 68102948 bytes, 0 no buffer
Received 410 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
841920 packets output, 110482012 bytes, 0 underruns
2415 output errors, 2415 collisions, 582 late collisions, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output

Based on the CLI output, which of the following is the most likely cause of the interface performance degradation?

Cevabı ve açıklamayı göster

Cevap: A duplex mismatch between the switch port operating in half-duplex and the connected host operating in full-duplex.

Cevap

A duplex mismatch between the switch interface operating in half-duplex and the connected end host operating in full-duplex is the primary cause of the late collisions and output errors.
Late collisions occur when a collision is detected after an interface has transmitted the first 64 bytes of a frame. In Ethernet networks, late collisions are most commonly caused by a duplex mismatch (where the local side is set to half-duplex and the remote side is set to full-duplex) or by cable length exceeding standard IEEE specifications. Because the remote full-duplex side does not listen before transmitting, it can send frames while the half-duplex side is mid-transmission, resulting in late collisions on the half-duplex interface.

Adım Adım Çözüm

1
Analyze the operational status and duplex setting from the show interfaces output.
The interface is operating in 'up/up' state at 100Mb/s Half-duplex.
Verifies physical connectivity and operational mode of the local switch interface.
2
Examine the interface error counters.
Output error counters show 2415 output errors, 2415 collisions, and 582 late collisions.
Identifies specific Layer 1/2 error metrics that indicate frame transmission anomalies.
3
Correlate late collision counters with network operational characteristics.
Late collisions occur when a collision is detected after the first 64 bytes (512 bits) of a frame have been transmitted.
Standard collisions are expected in normal half-duplex operation within the slot time, but late collisions strongly indicate a duplex mismatch where one end is configured for full-duplex and sends data regardless of carrier sense.

Anahtar Kavram

Duplex Mismatch Troubleshooting and Collision Counters
Tahmini Süre:1m 30s
ÖncekiSayfa 8 / 20Sonraki
Network Fundamentals Alıştırma Soruları — Cisco CCNA — Sayfa 8 | Examkin